What should officers look for when visually monitoring vehicles before speed detection?

When visually monitoring vehicles before speed detection, officers should focus on erratic driving behavior that may indicate speeding. This behavior, such as sudden acceleration or deceleration, weaving in and out of lanes, or following too closely behind other vehicles, can suggest that a driver is not adhering to speed limits. Observing these patterns allows officers to hone in on potential speed violations and take appropriate actions based on initial visual assessments.

The other options, while aspects of safe driving, do not provide as clear an indication of speed. Consistent lane changes could be a normal driving behavior, depending on the context, and do not necessarily signal speeding. The use of turn signals is a critical component of safe driving practices but again doesn't relate directly to speed. Distinct vehicle color might help identify a vehicle but does not provide any evidence or indicator of its speed. Thus, the focus on erratic driving behavior is key to determining potential speeding violations effectively.